The present invention relates to adapter cards for small computer systems. Specifically, an adapter card which may be configured in either a legacy, a plug and play, or a customer unique mapping mode is described.
Personal computers are designed with an open system which provides for expansion capabilities. The central processing for these computers is performed with circuitry which resides on a mother board. The mother board includes various slot interfaces which can receive devices which enhance the computer's utility. These devices may include network cards for connecting the computer to an external network, modems for communicating by telephone with other computers, hard drive and floppy drive controllers, etc. Once installed these devices may be addressed and utilized as a system resource.
All of these expansion devices include an adapter which contains various interface parameters for establishing operating conditions which are compatible with the system bus protocol. In prior art devices, these configuration parameters were preset in the adapter cards before installation and are not changed by the user, or only changed with special utilities software which requires considerable skill to operate. In some instances, conflicts in I/O (Input/Output) addresses, interrupt levels, etc., arise which cannot be resolved by the computer system when several of such expansion devices are in the computer.
A new configuration standard has been proposed which is referred to as a "plug and play" configuration. Adapter cards having the plug and play capability are individually configured by the computer system which assigns I/O addresses, interrupt levels, and other parameters during an initial power up sequence. The system BIOS or the operating system includes routines for individually addressing the adapter cards, assigning a handle for the adapter card, known as a Card Select Number (CSN), and determining the various operating requirements for the adapter cards. Conflicts between the identity of the cards are avoided as a result of the system conducting an inventory of all the connected devices which precedes the assignment of I/O addresses, interrupt levels, and the other parameters.
The use of plug and play adapter cards will undoubtedly prove advantageous to users who have a computer system which accepts the plug and play configuration. However, many systems currently in use do not have a system BIOS or operating system which provides plug and play capabilities. Adapter cards which are only configured for this configuration arc not functional in the older legacy systems which only support the pre-existing type of configuration.
After market adapters which are dedicated to a single configuration lack a versatility which permits a user to change resource allocations which is useful whether the system is a plug and play system or the older pre-plug and plug system. Ideally, adapter cards are desirable which are capable of both types of configuration, and which permit a user to modify the configuration through a companion utility program.